diff --git a/index.js b/index.js
index 3092a4d..ecec899 100644
--- a/index.js
+++ b/index.js
@@ -255,7 +255,7 @@ function format (obj) {
 }
 
 /**
- * Decode a RFC 6987 field value (gracefully).
+ * Decode a RFC 5987 field value (gracefully).
  *
  * @param {string} str
  * @return {string}